Nov. 22, 2019, 2:03 a.m.

Django

Django, SingletonModel, singleton, Model

Let's say you create a site with CMS based on Django, which must have some kind of dynamic site settings that will be available to the user. For example, the name of the site, some specialized information, while you take into account the possibility of multilingualism. What then can be used for this? I got the idea to use a database.

To implement this, the following is required:

  1. Creating a data model that will always contain only one object, that is, only one record. That is, it will be a Singleton Model.
  2. Prohibit deleting this entry and creating new ones in the Django admin panel
  3. The ability to use information from this model directly in the template, without loading the site settings in the view function.

Let's figure out in order how to implement this.

Sept. 20, 2018, 9:33 a.m.

Design Patterns

шаблоны проектирования, Синглетон, singleton

Цели

  1. Убедиться, что класс имеет только один экземпляр и предоставляет глобальную точку доступа к нему.
  2. Инкапсулированная "инициализация в определённый момент времени" или "инициализация при первом использовании".

Проблематика

Приложению нужен один и только один экземпляр объекта. Кроме того, необходимы ленивая инициализация и глобальный доступ.

July 5, 2017, 7:14 a.m.

QML

QML, singleton

In addition to C ++ classes in QML, Singleton can also use QML types, which are separate QML files.

This is also used by qmlRegisterSingletonType , but in order for this type to work as a singleton of the object, it is necessary to register the pragma Singleton in the QML file itself.

Let's make a small application that will also output several messages, while messages will be picked up through the Singleton QML Type method.

July 5, 2017, 6:05 a.m.

QML

qml, singleton, static

The notion of static methods that are used in QML differs somewhat from the classical one in C ++, when static methods are created in the class that can be used referring to the class name, rather than to a specific object. In the case of QML, things are somewhat different. In order to use such methods in QML, which are present in the C ++ class, it is necessary to register a Singleton object that will provide the required methods, and these methods should no longer be static in themselves. They should at least be labeled with the Q_INVOKABLE macro so that they can be used in QML.

To register Singleton , you need to use the qmlRegisterSingletonType function, which in addition to the standard parameters that are passed to qmlRegisterType, you must also pass the static singletonProvider function, which you also write yourself.

June 27, 2016, 2:47 a.m.

Ruby

method, Ruby, ruby lesson, ruby уроки, singleton, user guide, руководство пользователя

The behavior of an instance is determined by its class, but there may be times we know that a particular instance should have special behavior. In most languages, we must go to the trouble of defining another class, which would then only be instantiated once. In ruby we can give any object its own methods.

ruby> class SingletonTest
    |   def size
    |     print "25\n"
    |   end
    | end
   nil
ruby> test1 = SingletonTest.new
   #<SingletonTest:0xbc468>
ruby> test2 = SingletonTest.new
   #<SingletonTest:0xbae20>
ruby> def test2.size
    |   print "10\n"
    | end
   nil
ruby> test1.size
25
   nil
ruby> test2.size
10
   nil
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Last comments
Dec. 5, 2019, 4:15 p.m.
Evgenij Legotskoj

В этом слоте ваам нужно будет правильно смаппить координату. У QGraphicsView есть методы mapToScene, mapFromScene. Попробуйте использовать их.
LP
Dec. 5, 2019, 8:30 a.m.
Leonid Pivovarov

А без переопределения qgraphicsScene это сделать возможно? Есть же коорината нажатия кнопки мыши slotCustomMenuRequested(QPoint)
Dec. 5, 2019, 8:11 a.m.
Mihailll

//qDebug()<<"position:"<<event->pos(); //qDebug()<<"position:"<<event->screenPos(); qDebug()<<"position:"<<event->scenePos();
LP
Dec. 5, 2019, 8:09 a.m.
Leonid Pivovarov

Подскажите пожалуйста, К graphicsView я подключил обработку контекстного меню: сonnect(ui->graphicsView, SIGNAL(customContextMenuRequested(QPoint)), this, SLOT(slotCustomMenuRequest…
Dec. 4, 2019, 3:49 p.m.
Evgenij Legotskoj

resources_big - это флаг для сборки c++ приложения. Если Nuitka не предоставляет какой-либо функционал для прикручивания конфигурационных директив типа CONFIG при компиляции, то сомнева…
Now discuss on the forum
Dec. 5, 2019, 4:12 p.m.
Evgenij Legotskoj

Это уже кастомная стилизация. Придётся отключать обрамление и самостоятельно реализовывать ресайз окна, его перемещение, стиль и т.д. Вот статья, как отключить обрамление окна - QML …
Dec. 5, 2019, 4:27 a.m.
qml_puthon_user

Вот код, вдруг, кому поможет. Код основной формы: import QtQuick 2.12import QtQuick.Controls 2.12import QtQuick.Layouts 1.3import "./Components/Panels" as PanelsApplicationWindow{…
Dec. 5, 2019, 2:50 a.m.
Evgenij Legotskoj

Создавайте новые темы, чтобы не было всё в куче.
Dec. 4, 2019, 10:07 p.m.
qml_puthon_user

Спасибо за помощь! :) Я попытаю надежды в ожидании QtQuick3D от Riverbank'a. :)
V
Dec. 4, 2019, 7:02 a.m.
Vitali

Со временем распаковки соласен - для слабых ноутов это проблема и именно Nuitka мог бы здесь помочь, если бы заработало. А QtlFW - это уже фреймфорк для создания инсталятора из имеющихся па…
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